Chapter 13-Nuclei

NCERT Solutions for Class 12 Physics Chapter 13 – Nuclei

NCERT Solutions for Class 12 Physics Chapter 13 – Nuclei help students understand the physics of the atomic nucleus – its composition, size, mass, binding energy, radioactivity, and nuclear reactions. Myclass24 presents these solutions with clear derivations and numerical approaches that are aligned with the CBSE exam pattern. This chapter is directly connected to Chapter 12 and builds on the idea of the atomic nucleus introduced by Rutherford. Also, get subject-wise NCERT Solutions for class 12, for all chapters of Physics, check NCERT Solutions for class 12 Physics. 

Find the PDF of NCERT Solutions for Class 12 Physics Chapter 13 – Nuclei

Students can download the free PDF of NCERT Solutions for Class 12 Physics Chapter 13 – Nuclei from Myclass24. The PDF contains solved answers to all textbook questions, well-drawn diagrams wherever required, and explanations that match the CBSE marking scheme. Simply visit the Myclass24 website, navigate to Class 12 Physics, and find Chapter 13 to access or download the solution PDF at no cost. Having the PDF handy during revision allows you to study without an internet connection and make notes directly alongside the solutions.

Chapter 13 Details at a Glance

What is Chapter 13 – Nuclei About?

Chapter 13 dives deep into the nucleus itself. The nucleus is made of protons and neutrons (collectively called nucleons). The number of protons is the atomic number Z, and the total number of nucleons is the mass number A. The radius of a nucleus is approximately R = R₀A^(1/3), which tells us nuclear density is roughly constant – a remarkable fact.

One of the most important concepts in this chapter is nuclear binding energy. When nucleons come together to form a nucleus, the total mass of the nucleus is slightly less than the sum of the masses of its constituent nucleons. This mass defect (Δm) is converted into binding energy using Einstein's formula: E = Δmc². A higher binding energy per nucleon means a more stable nucleus. The binding energy per nucleon curve peaks around iron (Fe-56), explaining why both fission of heavy nuclei and fusion of light nuclei release energy.

Radioactivity is a naturally occurring process in which unstable nuclei emit radiation to become more stable. There are three types: alpha decay (emission of a helium-4 nucleus), beta decay (emission of an electron or positron), and gamma decay (emission of a high-energy photon). The law of radioactive decay states that the number of nuclei decreases exponentially: N = N₀e^(−λt), where λ is the decay constant. Half-life (T₁/₂ = 0.693/λ) is the time for half the nuclei to decay.

Nuclear fission is the splitting of a heavy nucleus (like Uranium-235) into two lighter nuclei, releasing enormous energy – the basis of nuclear power plants and atomic bombs. Nuclear fusion is the combining of light nuclei (like hydrogen isotopes) to form a heavier nucleus, releasing even more energy per unit mass – the process powering the sun.

Myclass24's solutions for Chapter 13 include well-explained answers to all theoretical and numerical questions, helping students score confidently on this high-weightage chapter.

How to Use NCERT Solutions for Chapter 13 Effectively

Start by reading the relevant pages in your NCERT textbook and trying the questions on your own. Then cross-check with Myclass24's solutions to see where your approach differed. Pay attention to how formulae are applied, how diagrams are drawn, and how marks are allocated in multi-step problems. Make a separate notes page for key formulae and definitions from this chapter. Attempt past CBSE board papers and sample papers on Chapter 13 after completing the NCERT exercises. This cycle of reading, solving, and reviewing is the most reliable way to prepare.